Fiber insulation blanket and method of manufacture

ABSTRACT

A fiber blanket formed with a blend of constituent fibers is disclosed. In one disclosed embodiment, a cellulose fiber blanket is formed having a blend of cellulose fibers comprising approximately 85-90% by weight cellulose, resilient fibers comprising approximately 10% by weight, and the balance being adhesive plastic fibers. The fibers are then formed into a blanket having an R-value at least 4.0 per inch.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of PCT Application PCT/US2005/039605 with an International filing date of Nov. 02, 2005, which claims the benefit of U.S. Provisional Application Ser. 60/517530, filed on Nov. 04, 2003, and which are both incorporated, in their entirety, herein by reference.

BACKGROUND

1. Field of the Disclosure

This disclosure relates generally to the composition and manufacture of paper fiber insulation products.

2. The Prior Art

Background

Currently, the bulk of thermal insulation material is made from glass wool and is sold in the form of a blanket. The shape and size of such blankets allows for convenient shipping and installation. An alternative to glass wool is cellulose insulation.

The industry standard R-value allows for the comparing of a material's thermal insulating capability. The higher the R-value number, the greater is the material's ability to insulate.

The insulating capability of a given blanket is largely determined by the density of the constituent fibers of the blanket. Hence, the higher the density the lower the R-value. The hollow nature of cellulose fiber provides a potential for a higher R-value than glass wool.

Recently adopted building codes throughout the US have set a minimum of R-15 insulation within a 2×4 residential wall. This translates to a minimum R-value of 4.1 per inch and effectively prohibits the use of prior art cellulose insulation products in the cities and counties where this code has been adopted.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a conceptual diagram of a process for forming a fiber insulation blanket in accordance with the teachings of this disclosure.

DETAILED DESCRIPTION

Persons of ordinary skill in the art will realize that the following description is illustrative only and not in any way limiting. Other modifications and improvements will readily suggest themselves to such skilled persons having the benefit of this disclosure. In the following description, like reference numerals refer to like elements throughout.

FIG. 1 is a conceptual diagram of a system 100 for forming a cellulose fiber insulation blanket. The process begins with the dosing and mixing of the constituent fibers, contained in towers 105, 110, and 115 of an air-lay machine, being transferred to a forming head 120 for shaping.

As will be described more fully below, in a preferred embodiment, fiber insulation blankets of the present disclosure comprise a preferably homogenous composition of cellulose fibers, resilient fibers, and adhesive fibers, and it is desired that the mixture resulting from the forming head process be as thoroughly mixed as possible.

The blended fibers 121 are then deposited onto the surface of a wire, typically a slotted conveyor belt, thereby forming a fiber blanket 125. The blanket 125 is then transported to a thermal forming station 130.

Heated air is then drawn through the blend to soften and melt the adhesive plastic fibers, thereby adhering the constituent fibers into a matrix. Cool air is then drawn through the matrix solidifying the melted fibers and forming a continuous, coherent blanket 135. Preferably, a forming head in conjunction with a thermal bonding oven is suitable for this type of non-woven process.

The blanket 135 may then be formed into batts 140 of a desired size as required.

Finding an optimal balance between resilience and adhesion is critical so as to provide a product with good fiber compression recovery, low density and high R-value. For example, the finished product must return as closely as possible to its original thickness and shape after it has been compressed for packaging in order to maintain the stated R-value. Compression recovery has a strong effect on the cost of shipping and is therefore a critical element in the commercial viability of such products.

To achieve these goals, in one disclosed aspect, a fiber blanket is formed by using 85-90% by weight cellulose fibers with the resilient and adhesive plastic fibers comprising the balance. In a further disclosed embodiment, a blend by weight of 75% cellulose, 20% resilient fiber and 5% adhesive fiber is used. In a further disclosed embodiment, a blend by weight of 85% cellulose, 10% resilient fiber and 5% adhesive fiber is used. In yet a further disclosed embodiment, a blend by weight of about 89% cellulose, 9% resilient fibers and 2% adhesive fibers will produce the same physical properties at lower cost. These blends preferably yield a blanket whose density can be varied from 0.8-1.5 pounds per cubic foot with an R-value ranging from 3.8-4.2, and preferably at least 4.0.

More details of exemplary constituent fibers suitable for use in this disclosure will now be disclosed.

Referring first to the cellulose constituent, in one preferred embodiment a cellulose fiber which complies with ASTM standard C739-91 is utilized. Such a loose-fill insulation fiber may be obtained from Cottonwood Manufacturing, Inc., the assignee of the present disclosure.

Additionally, the cellulose fibers may be treated to provide fire retardant or mold resistance properties. For example, the cellulose fibers may be impregnated with a liquid chemical formula as disclosed in U.S. Pat. Nos. 5,534,301 and 6,025,027 to Shutt, also assigned to the assignee of the disclosure and each incorporated by reference as though fully set forth herein, to provide fire and mold protection. Liquid additives have a superior dispersion rate because solids in solution are readily absorbed by the cellulous fibers and quickly diffuse throughout the hollow core and mass of each fiber. Subsequent drying of the cellulose fibers leaves a homogenous precipitation of the impregnates as opposed to conventional powder systems, which exhibit weak adhesion to the surfaces of cellulose fibers. Consequently, the weight of such liquid chemical impregnates contributes up to two-thirds less weight to the fibers, as compared with powder alternatives. This reduction in weight contributes to the lower density of the final product.

Preferred treatments include liquid borates. In one embodiment, liquid borates are applied directly to the fibers during mixing. In a further preferred embodiment, liquid borates are employed which are converted to boric acid inside the cellulose fibers through the use of acid such as sulfuric acid. Additional treatments may also include dyes and perfumes, for example, for improved user acceptance of the product.

Referring now to the resilient plastic constituent fiber, a polyester staple may be employed. Preferably, the resilient plastic fibers are of hollow polyester having a denier of 15 and a length of not less than 32 millimeters. Fibers suitable for use in this disclosure preferably have a melting point of approximately 219° C., a denier of approximately 6-15, and a length of approximately 25-51 millimeters. Such fibers may include, KoSa® types 209 or 210 or equivalents.

The resilient fibers may be crimped for increased resilience, and hollow for increased denier sizing so as to exhibit increased springiness and resiliency enabling the blankets of this disclosure to be compressed so as to assume less bulk for shipping at lower cost, while subsequently resuming substantially all of its bulk thereafter in use for improved thermal insulation properties.

Referring now to the adhesive constituent fiber, in a preferred embodiment, adhesive plastic fiber is utilized that comprises a polyester core and an activated co-polyethylene sheath. The sheath preferably has a melting point of no more than 128° C., and a denier of not more than 3 to promote as complete dispersal and homogenization of the fibers as possible. Additionally, the adhesive plastic fibers have a length of not more than 8 millimeters, and preferably a length of not more than 6 millimeters to promote optimal bonding with the other constituent fibers. Suitable adhesive fibers include KoSa® types 254 or 255 Celbond® Bicomponent Fiber or equivalents.

As was described above, the adhesive fibers typically are heated to adhere and form a blanket. In an alternative embodiment, the adhesive fibers may be treated with material that would allow the use of Radio Frequency (RF) heating. In such an embodiment, the blanket may the be formed using RF energy rather than prior art gas ovens. Such an RF process is far more efficient that traditional heating methods.

It is contemplated that the adhesive fibers may be produced containing materials such as carbon thereby permitting heating by induction. It is also contemplated that additives such as compounds of the alkyl aryl sulfonate and alkyl aryl polyester alcohol groups could be applied to the fiber surfaces to render them susceptible to dielectric heating. It is contemplated that when using a RF reactive material, the co-polyethylene sheath may be unnecessary, resulting in a lower cost adhesive materials.

Examples of non-woven formulas and compositions will now be disclosed.

In a first exemplary composition, a blend of 85% cellulose fiber, 10% resilient fiber, and 5% adhesive fiber was used.

In a second exemplary composition, a blend of 89% cellulose fiber, 9% resilient fiber, and 2% adhesive fiber.

In both examples, the resilient fiber comprised the KoSa Type 210, and the adhesive fiber comprised the KoSa Type 255, as disclosed above.

The materials were processed with an opening and dosing station, an air-laid forming head and a thermal bonding oven supplied by Bettarini & Serafini srl of Prato, Italy. The R-value testing performed per ASTM C-518, and Compression Recovery testing performed per ASTM C-167.

The results are presented in Table 1: Loft Density Compression Recovery R-value/in. Sample #1 16 kg/m3 75% 85% 4.0 90 mm (1 lb/cu ft Sample #2 15 kg/m3 80% 97% 4.1 90 mm (0.81 lb/cu ft)

While embodiments and applications of this disclosure have been shown and described, it would be apparent to those skilled in the art that many more modifications and improvements than mentioned above are possible without departing from the inventive concepts herein. The disclosure, therefore, is not to be restricted except in the spirit of the appended claims. 

What is claimed is:
 1. A fiber blanket formed with a blend of constituent fibers comprising: cellulose fibers comprising approximately 85-90% by weight cellulose; resilient fibers comprising approximately 10% by weight; adhesive plastic fibers; and said constituent fibers being formed into a blanket having an R-value of at least 4.0 per inch.
 2. The blanket of claim 1, wherein said blend of constituent fibers comprises a blend by weight of 85% cellulose, 10% resilient fiber and 5% adhesive fiber.
 3. The blanket of claim 1, wherein said blend of constituent fibers comprise a blend of 89% cellulose fiber, 9% resilient fiber, and 2% adhesive fiber.
 4. The blanket of claim 3, wherein the density of said blanket may be varied from 0.8-1.5 pounds per cubic foot.
 5. The blanket of claim 1, wherein said cellulose fibers are treated (are treated) to provide fire retardant properties.
 6. The blanket of claim 5, wherein said properties are provided using a liquid additive.
 7. The blanket of claim 6, wherein said liquid additive include a liquid borate.
 8. The blanket of claim 1, wherein said cellulose fibers are treated to provide mold resistance properties.
 9. The blanket of claim 8, wherein said properties are provided using a liquid additive.
 10. The blanket of claim 9, wherein said liquid additive include a liquid borate.
 11. The blanket of claim 1, wherein said adhesive fibers contain a material permitting heating by induction.
 12. The blanket of claim 11, wherein said material comprises carbon.
 13. The blanket of claim 1, wherein said adhesive fibers contain an additive permitting dielectric heating.
 14. The blanket of claim 13, wherein said additive comprises a compound of the alkyl aryl sulfonate group.
 15. The blanket of claim 13, wherein said additive comprises a compound of the alkyl aryl polyester alcohol group. 